JP5846638B2 - Method for coating in-mold of fiber reinforced plastic material and method for forming coating film of molded product thereof - Google Patents

Description

  The present invention relates to a method for coating a fiber-reinforced plastic material using an epoxy resin as a matrix resin and a method for forming a coating film on the molded product.

  Fiber reinforced plastics (FRP Reinforced Plastics: hereinafter referred to as FRP material or simply FRP) are excellent in rigidity, mechanical strength, moldability, etc., and are lightweight. It has come to be used in many fields such as parts, housing equipment parts, and electrical product parts. However, FRP molded products have surface defects such as burrows, pinholes, microcracks, and fiber patterns (fiber shape floats). Even if the FRP molded product is painted by a normal method, it has a finished quality. It is difficult to form a sufficient coating film.

  As a method for effectively improving these surface defects, a method of applying a thermosetting resin composition called a gel coat to the surface of an FRP molded product is known. In particular, in recent years, as a construction method with less impact on the environment, such a thermosetting resin composition has been injected into the gap provided between the surface of the plastic molded body molded in the mold and the mold surface. An in-mold coating method (in-mold coating method) has been attracting attention in which a thermosetting resin composition is cured in a mold to produce an integrally molded body in which a coating is in close contact with the surface of an FRP molded product.

  As a conventional in-mold coating composition, for example, a radical polymerization type heat according to Patent Documents 1 to 3, for example, in accordance with a matrix resin of FRP material (also referred to as a base resin, a base material plastic, a resin that becomes a base material after molding) A curable resin composition is mentioned. In recent years, in order to obtain a lightweight, high-strength, high-rigidity FRP molded product, carbon fibers are increasingly used as reinforcing fibers for FRP materials. When carbon fiber is used as the reinforcing fiber, an epoxy resin having high adhesion to the FRP material is preferably used as the matrix resin. When an epoxy resin is used as the matrix resin of the FRP material, there are few functional groups with excellent adhesion such as hydroxyl groups on the surface of the FRP molded product obtained depending on the curing type. Even when the coating composition is used, the adhesion with a colored coating film to be formed later may be insufficient.

  In Patent Document 4, as a mold-in-coating composition, a radical-polymerizable compound in which a monofunctional radical-polymerizable compound having an epoxy group and / or an acid anhydride group is blended for imparting adhesion to an epoxy resin. Although a thermosetting resin composition is disclosed, this composition improves adhesion to FRP molded products using an epoxy resin as a matrix resin, but finish and adherence to a finished colored coating film Was insufficient.

  Further, Patent Document 5 discloses that 2-hydroxyethyl acrylate is present in the thermosetting resin, and the adhesion between the base material and the coating layer is improved. Even when it was put in the in-mold coating composition, the adhesion to a colored coating film to be formed later was insufficient.

JP-A-5-70712 JP-A-10-204135 JP-A-6-286008 JP 2003-138032 A JP-A-5-59136

  An object of the present invention is to provide an in-mold coating that is excellent in adhesion and finish with a fiber reinforced plastic material using an epoxy resin as a matrix resin, and excellent in adhesion and water resistance with a colored coating film to be formed later. It is to provide an in-mold coating method capable of obtaining a film.

  As a result of intensive studies in order to solve the above problems, the present inventors have found that in the in-mold coating method of a fiber reinforced plastic material using an epoxy resin as a matrix resin, the in-mold coating composition contains polymerizable unsaturated At least one specific weight-average molecular weight resin (A) selected from a group-containing urethane resin, a polymerizable unsaturated group-containing epoxy resin, and a polymerizable unsaturated group-containing polyester resin, and a specific compound having a molecular weight of 156 to 280 (B) and an in-mold coating composition containing a specific amount of a compound (C) having one or more hydroxyl groups and two or more (meth) acryloyl groups in one molecule and an organic peroxide (D). As a result, it was found that a film excellent in adhesion and water resistance between the fiber reinforced plastic material and a colored coating film to be formed later was obtained, and the present invention was completed.

That is, the present invention provides the following in-mold coating method:
Item 1. The fiber reinforced plastic material is heated and molded in the mold, and then the in-mold coating composition is injected between the obtained molded product and the inner wall of the mold to cure the in-mold coating composition, and then the coating is performed. In the in-mold coating method including the step of taking out the formed molded product from the mold,
The matrix resin used for the fiber reinforced plastic material is an epoxy resin,
And the in-mold coating composition comprises:
(A) a resin having a weight average molecular weight of 3,000 to 80,000 selected from a polymerizable unsaturated group-containing urethane resin, a polymerizable unsaturated group-containing epoxy resin, and a polymerizable unsaturated group-containing polyester resin;
(B) a compound represented by the following general formula (I) having a molecular weight of 156 to 280,

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a C 1-8 divalent organic group having no hydroxyl group.)
(C) a compound having one or more hydroxyl groups and two or more (meth) acryloyl groups in one molecule, and (D) an organic peroxide, and component (A), component (B) and component ( The solid content of the component (A) is 5 to 80 parts by mass based on 100 parts by mass of the total solid content of C),
The solid content of the component (B) is 10 to 85 parts by mass,
The solid content of the component (C) is 1 to 10 parts by mass,
The solid content of component (D) is 0.1 to 5 parts by mass,
An in-mold coating method characterized in that:

  Item 2. Item 2. The in-mold coating method according to Item 1, wherein the curing agent used in the fiber-reinforced plastic material is at least one selected from an amine compound, an acid anhydride compound, a polyimide compound, and an imidazole compound.

  Item 3. Item 3. A molded product obtained by the in-mold coating method according to Item 1 or Item 2.

  Item 4. Item 4. A method for forming a coating film of a molded product, comprising forming at least one colored coating film on the molded product according to Item 3.

  Item 5. A coated article coated by the method for forming a coating film according to Item 4.

  According to the in-mold coating method of the present invention, it is excellent in adhesion and finish with a fiber reinforced plastic material using an epoxy resin as a matrix resin, and excellent in adhesion and water resistance with a colored coating film to be formed later. An in-mold coating film can be obtained.

≪In-mold coating composition≫
≪Component (A) ≫
The in-mold coating composition used in the present invention comprises a polymerizable unsaturated group-containing urethane resin (A-1), a polymerizable unsaturated group-containing epoxy resin (A-2), and a polymerizable unsaturated group-containing polyester resin (A- The resin (A) having a weight average molecular weight of 3,000 to 80,000 selected from 3) is contained.

  The weight average molecular weight of these resins may vary depending on the type of the resin, but is 3,000 to 80,000, preferably 5,000 from the viewpoints of adhesion to the substrate, compatibility with other components, and finish. It is suitable to be in the range of ˜70,000, more preferably 10,000 to 60,000.

In the present specification, the weight average molecular weight (Mw) is measured by a gel permeation chromatograph (gel permeation chromatograph: GPC) using a standard polystyrene calibration curve.
“HLC-8120GPC” (trade name, manufactured by Tosoh Corporation) is used as the gel permeation chromatograph, and one “TSKgel G4000HXL”, two “TSKgel G3000HXL”, and “TSKgel G2000HXL” are used as columns. A total of four (1 product name, all manufactured by Tosoh Corporation) are used, and a differential refractometer is used as a detector. The mobile phase is tetrahydrofuran, the measurement temperature is 40 ° C., and the flow rate is 1 mL / min. It can be measured under conditions.

  In the present specification, the polymerizable unsaturated group means an unsaturated group capable of radical polymerization. The unsaturated group capable of radical polymerization is a functional group having a carbon-carbon double bond (also called a polymerizable double bond), for example, vinyl group, (meth) acryloyl group, (meth) acrylamide group, A vinyl ether group, an allyl group, etc. can be mentioned.

  In the present specification, “(meth) acrylate” means “acrylate or methacrylate”. “(Meth) acrylic acid” means “acrylic acid or methacrylic acid”. “(Meth) acryloyl” means “acryloyl or methacryloyl”. “(Meth) acrylamide” means “acrylamide or methacrylamide”.

  As the polymerizable unsaturated group-containing urethane resin (A-1), for example, a reaction product of a polyisocyanate compound (a), a compound (a2) having a polymerizable unsaturated group and an active hydrogen group in one molecule, Or further, the reaction material of these and a polyol compound (a3) is mentioned.

  The polyisocyanate compound (a1) is not particularly limited, and examples thereof include polyisocyanates such as aromatic compounds, aliphatic compounds, cycloaliphatic compounds, and alicyclic compounds. Among them, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, modified diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate Diisocyanates such as 1,3-bibis (isocyanatomethyl) cyclohexane or trimers thereof are preferably used. The weight average molecular weight of the polyisocyanate compound (a1) is preferably 150 to 700 from the viewpoint of reactivity with a hydroxyl group.

The compound (a2) having a polymerizable unsaturated group and an active hydrogen group in one molecule is, for example, a compound having one active hydrogen group and one or more polymerizable unsaturated groups in one molecule. The active hydrogen group is a group that can react with the isocyanate group of the polyisocyanate compound (a1), and examples thereof include a hydroxyl group and an amino group.
Specific examples include hydroxyl group-containing (meth) acrylates and amino group-containing (meth) acrylates.

  Examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate; glycerin di (meth) acrylate, alkyl glycidyl ether, and glycidyl. Examples include adducts of glycidyl group-containing compounds such as (meth) acrylate and (meth) acrylic acid.

  Examples of the amino group-containing (meth) acrylate include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, Nt-butylaminoethyl ( And (meth) acrylate.

  The polyol compound (a3) is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, 1,4- Butanediol, polybutylene glycol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, hydrogenated bisphenol A, polycaprolactone, trimethylolethane, trimethylolpropane, polytrimethylolpropane, pentaerythritol, polypentaerythritol, Sorbitol, mannitol, arabitol, xylitol, galactitol, glycerin, polyglycerin Polyhydric alcohol such as polytetramethylene glycol, polyethylene oxide, polypropylene oxide, polyether polyol having at least one structure of block or random copolymerization of ethylene oxide / propylene oxide, polyhydric alcohol or polyether polyol and anhydrous Caprolactone-modified polyols such as maleic acid, maleic acid, fumaric acid, itaconic anhydride, itaconic acid, adipic acid, isophthalic acid, and other polybasic acids, caprolactone-modified polytetramethylene polyols, polyolefin polyols And polybutadiene-based polyols such as hydrogenated polybutadiene polyol.

  Moreover, as (A-1), a commercial item can also be used. For example, Nippon Synthetic Chemical Industry Co., Ltd., purple light series UV-2000B, UV3000B, UV-3200B, UV-3300B, UV-3310B, UV3700B, UV-6640B, Negami Kogyo Co., Ltd., Art Resin UN-9000PEP, UN- 7600, UN-333, UN-1255, UN-9200, UN-7700, UN-5500, UN-5507, UN-55B0, UN-6301.

  As the polymerizable unsaturated group-containing epoxy resin (A-2), for example, an epoxy compound and a polymerizable unsaturated group-containing carboxylic acid have a carboxyl group equivalent to, for example, 0.5 to 1 equivalent to 1 equivalent of epoxy group. And those produced by reacting at a ratio of 0.5. Examples of the epoxy compound used here include a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, a phenol novolac type epoxy compound, and a cresol novolac type epoxy compound. Examples of the polymerizable unsaturated group-containing carboxylic acid include acrylic acid and methacrylic acid.

A commercial item can also be used as (A-2). For example, NK Oligo EA-7120, EA-7140, EA-7420 manufactured by Shin-Nakamura Chemical Co., Ltd., Lipoxy R-802, H-600, R-770, NSR-112, R-8800 manufactured by Showa Denko KK Can be mentioned.
As the polymerizable unsaturated group-containing polyester resin (A-3), for example, the polyol compound (a3) mentioned in the above section (A-1), the polymerizable unsaturated group-containing polycarboxylic acid and / or polymerizable. It can be produced by reacting an unsaturated group-containing carboxylic acid with a known method, and further reacting with other polycarboxylic acid and / or carboxylic acid, if necessary. Further, for example, a polyester resin having a polymerizable unsaturated group at a terminal by a reaction between a polyester polyol having a hydroxyl group at the terminal and a polymerizable unsaturated group-containing polycarboxylic acid and / or a polymerizable unsaturated group-containing carboxylic acid. Can be manufactured.

  Examples of the polymerizable unsaturated group-containing polycarboxylic acid and / or polymerizable unsaturated group-containing carboxylic acid include (meth) acrylic acid, fumaric acid, tetrahydro (anhydride) phthalic acid, (anhydrous) itaconic acid and the like. be able to.

  Examples of other polycarboxylic acids and / or carboxylic acids include adipic acid, (anhydrous) phthalic acid, (anhydrous) trimellitic acid, (anhydrous) succinic acid, and (anhydrous) hexahydrophthalic acid. .

  A commercial item can also be used as (A-3). Examples thereof include Sandoma CU653 and GC130 manufactured by DH Material Co., Ltd., Rigo rack 158BQT, M-411-1, M-543, and KRN-550T manufactured by Showa Denko KK. Examples of (A-3) having a polymerizable unsaturated group at the terminal include EBECRYL436, EBECRYL438, EBECRYL524, and EBECRYL885 manufactured by Daicel-Cytec Corporation.

  These polymerizable unsaturated group-containing resins as the component (A) may be used alone or in combination of two or more.

≪Ingredient (B) ≫
The in-mold coating composition used in the present invention is a compound (B) represented by the following general formula (I) having a molecular weight of 156 to 280,

(Wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents a C 1-8 divalent organic group having no hydroxyl group).

  A component (B) is a component which can be copolymerized with a component (A) and the component (C) mentioned later.

Examples of the divalent organic group having 1 to 8 carbon atoms represented by R ² include a linear, branched or cyclic alkylene group having 2 to 8 carbon atoms, an alkoxyalkylene group having 2 to 8 carbon atoms, and 2 to 2 carbon atoms. 8 halogenated alkylene group, polyethylene glycol skeleton excluding terminal hydroxyl group, polypropylene glycol skeleton excluding terminal hydroxyl group, polybutylene glycol skeleton excluding terminal hydroxyl group, neopentyl glycol excluding terminal hydroxyl group, or allyl group. However, R ² does not have a hydroxyl group.

  Specifically, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol diacrylate, 1,3-butane Diol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanedimethanol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate, polyethylene glycol di (meth) acrylate having a polymerization degree of 2 or 3, polypropylene glycol di (meth) acrylate having a polymerization degree of 2, and the like. More preferred examples include 1,3-butanediol di (meth) acrylate and 1,4-butanediol di (meth) acrylate.

  Component (B) may be used alone, or may be used as a mixture of two or more thereof.

  From the viewpoint of adhesion to a fiber reinforced plastic material, it is suitable that the molecular weight is in the range of 156 to 280, preferably 170 to 250. By blending a specific amount of the component (B), it can penetrate into the base material, and adhesion can be imparted by the anchor effect of the component (B). In addition, the component (B) is excellent in the balance between the compatibility with other components and the reactivity, and a coating film having a good finish can be obtained.

  In addition, since the component (B) has two (meth) acryloyl groups as in the general formula (I), the component (B) has excellent compatibility with the component (A) and the component (C) described later. It is considered that not only the material penetrated but also a high cohesive force was obtained, and the adhesion was improved.

≪Ingredient (C) ≫
The in-mold coating composition used in the present invention contains a compound (C) having one or more hydroxyl groups and two or more (meth) acryloyl groups in one molecule.

  Examples of the compound having one or more hydroxyl groups and two or more (meth) acryloyl groups in one molecule include the following.

  For example, as a compound having one hydroxyl group and two (meth) acryloyl groups, glycerol di (meth) acrylate, 2-hydroxy-3- (meth) acryloyloxypropyl (meth) acrylate, one or more hydroxyl groups and Examples of the compound having three or more (meth) acryloyl groups include pentaerythritol tri (meth) acrylate, isocyanuric acid ethylene oxide-modified di (meth) acrylate, and dipentaerythritol penta (meth) acrylate.

  As a commercial product of a compound having one hydroxyl group and two (meth) acryloyl groups, Aronix M-215 (manufactured by Toagosei Co., Ltd., Aronix is a registered trademark of Toagosei Co., Ltd.), NK ester 701, NK ester 701A ( Shin-Nakamura Chemical Co., Ltd.).

As a commercial product of a compound having one or more hydroxyl groups and three or more (meth) acryloyl groups,
Aronix M-313, M-315, M-325, M-327, M-305, M-306, M-452, M-450, M-403, M-400, M-402, M-404, M -406, M-405 (manufactured by Toagosei Co., Ltd.), NK ester A-TMM-3, NK ester A-TMM-3L, NK ester A-TMM-3LM-N (manufactured by Shin-Nakamura Chemical Co., Ltd.), etc. Is mentioned.

  Among these, compounds having one or more hydroxyl groups and three or more (meth) acryloyl groups are preferable from the viewpoint of adhesion, reactivity, and compatibility with other components.

  The weight average molecular weight of component (C) is preferably 300 to 3000 from the viewpoint of compatibility with other components.

≪Organic peroxide (D) ≫
The in-mold coating composition used in the present invention contains an organic peroxide (D). The component (D) is thermally decomposed by the heat of the mold or the molded body to generate radicals, and initiates radical polymerization reaction of double bonds contained in the mold coating composition. Has the effect of curing.

  Examples of such an organic peroxide (D) include bis (4-t-butylcyclohexyl) peroxydicarbonate, t-amylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, dicarbonate. Milperoxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-octyl peroxy octoate, t-amyl peroxy octoate, t-butyl peroxy octoate, t-octyl peroxy benzoate 1,1-di-t-butylperoxycyclohexane, t-butylperoxy-3,5,5-trimethylhexanoate, 2,2-di-t-butylperoxybutane, t-butylperoxyisopropyl Carbonate and t-amyl peroxybenzo Over preparative like are preferably exemplified.

<Others>
The in-mold coating composition used in the present invention can further contain an inorganic filler, a conductivity imparting agent, and a dispersing agent as required.

  Preferred examples of the inorganic filler include calcium carbonate, talc, barium sulfate, aluminum hydroxide, and clay. These inorganic fillers are blended for the purpose of dispersing the shrinkage stress accompanying the film curing, improving the adhesion to the molded body, smoothing the surface irregularities, and improving the appearance of the molded body surface. Among these, from the viewpoint of adhesion to the substrate, it is preferable to contain at least one kind of inorganic particles such as calcium carbonate and talc having a volume-based average particle diameter of 0.1 μm to 20 μm.

  Examples of the conductivity-imparting agent include conductive carbon black, graphite, metal oxide (titanium oxide, zinc oxide, tin oxide, etc.), conductive surfactant, metal powder, a composite material in which a metal is attached to the carrier surface, carbon Examples thereof include fibers, and conductive carbon black is preferably used particularly from the viewpoint of stability of volume resistivity.

  The dispersant is not particularly limited as long as it is used for the purpose of dispersing a conductivity imparting agent in this technical field. For example, a polyamide resin, a hydroxyl group-containing carboxylic acid ester, a long-chain polyaminoamide, and a high molecular weight acid ester are used. Salt, long chain polyaminoamide and high molecular weight polycarboxylic acid salt, long chain polyaminoamide and polar acid ester salt, high molecular weight unsaturated acid ester, modified polyurethane, modified polyacrylate, polyetherester type anionic activator, naphthalene A sulfonic acid formalin condensate salt, an aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonylphenyl ether, stearylamine acetate, and the like can be used.

  By using the dispersant, the dispersibility of the conductivity imparting agent is improved, and a cured coating film having good conductivity can be obtained.

The in-mold coating composition used in the present invention may further contain an internal mold release agent, if necessary.
As the internal mold release agent, for example, those having a melting point of 125 ° C. or lower can be used particularly suitably. If the melting point of the release agent is, for example, 125 ° C. or less, a desired release effect can be sufficiently obtained. This is because, even if the temperature of the mold is about 40 to 110 ° C., considering that the molten thermoplastic resin having a high temperature of 200 to 240 ° C. is cooled and solidified in the mold, the in-mold coating composition This is because it is considered that the surface temperature of the molded body at the time when is injected is sufficiently higher than the melting point of 125 ° C. of the release agent. Examples of such release agents include stearic acid, stearates such as zinc stearate, aluminum stearate, magnesium stearate, calcium stearate, soybean oil lecithin, silicone oil, fatty acid ester and fatty acid alcohol dibasic acid. Mention may be made of esters.

  The in-mold coating composition used in the present invention further includes, as optional components, a photoinitiator, an ultraviolet absorber, a hindered amine light stabilizer, an antifoaming agent, a leveling agent, a wax, an antioxidant, a dye, a coloring pigment, Thermoplastic resins, other polymerizable unsaturated compounds (E), curing accelerators such as amine compounds and metal oxides, and the like can be added.

  The polymerizable unsaturated compound (E) is a compound other than those corresponding to the component (A), the component (B) and the component (C) of the present invention, and has a polymerizable unsaturated group in its chemical structure. The compound is not particularly limited as long as it is a compound having at least one.

≪Content of each component in the in-mold coating composition≫
The solid content of component (A), component (B), component (C), and component (D) in the in-mold coating composition used in the present invention is in the following range from the viewpoint of adhesion to the substrate. It is.

Based on 100 parts by mass of the total solid content of component (A), component (B) and component (C),
The solid content of the component (A) is 5 to 80 parts by mass,
Preferably, 12 to 78 parts by mass, more preferably 25 to 62 parts by mass,
The solid content of the component (B) is 10 to 85 parts by mass,
Preferably, 20 to 80 parts by mass, more preferably 30 to 72 parts by mass,
The solid content of the component (C) is 1 to 10 parts by mass,
Preferably, 2 to 8 parts by mass, more preferably 3 to 8 parts by mass,
The solid content of component (D) is 0.1 to 5 parts by mass,
Preferably, it is 0.5-3 mass parts.

  Moreover, about the other component used as needed for this invention, the following range is preferable.

  The solid content in the case of blending the inorganic filler is 200 masses based on the total solid content of 100 parts by mass of the component (A), the component (B) and the component (C) from the viewpoint of adhesion to the substrate. A range of 10 parts by weight or less, preferably 10 to 150 parts by weight is suitable.

  Solid content in the case of mix | blending an electroconductivity imparting agent is 0.1-30 on the basis of 100 mass parts of total solid content of a component (A), a component (B), and a component (C) from an electroconductive point. A part by weight, preferably 0.5 to 20 parts by weight is suitable.

  The in-mold coating composition injected into the mold preferably has a viscosity in the range of 70 to 50,000 mPa · s at 20 ° C.

  If the viscosity of the in-mold coating composition is 70 mPa · s or more at 20 ° C., the in-mold coating composition flows uniformly in the mold to suppress air entrainment and prevent leakage from the mold. Fluidity is obtained. Moreover, when the viscosity is 50,000 mPa · s or less, excessive high-pressure injection is not required when the in-mold coating composition is injected into the mold, which is preferable.

  The in-mold coating composition used in the in-mold coating method of the present invention is such that component (B) has a molecular weight of 156 to 280 until it is injected into the mold and the in-mold coating composition is cured. Can penetrate into the FRP material and copolymerize with both component (A) and component (C) to obtain strong adhesion and cohesion between the in-mold coating layer and the matrix resin. it can. In addition, since component (C) has a (meth) acryloyl group and a hydroxyl group, it is excellent in compatibility with component (A) and component (B), and after injecting and curing the in-mold coating composition. A hydroxyl group can be present in the cured product. Therefore, it is considered that a strong adhesive force and cohesive force can be obtained with a colored coating film formed later based on the hydroxyl group.

≪In-mold coating method≫
According to the in-mold coating method of the present invention, a fiber reinforced plastic material (hereinafter sometimes abbreviated as FRP material) is heated and molded in a mold, and then the inside of the mold is interposed between the obtained molded product and the mold inner wall. After the coating composition is injected and the in-mold coating composition is cured, the coated molding is removed from the mold. The matrix resin used for the FRP material coated in the mold is an epoxy resin.

  As the above-mentioned in-mold coating method (in-mold coating method, In-Mold Coating, IMC), a conventional method of molding in a mold can be used without any particular limitation, but Japanese Patent Publication No. 55-9291 is preferable. The method described in Japanese Patent Laid-Open No. 61-273921 can be used.

  That is, a reinforcing fiber, which will be described later, is placed between molds having the shape of a target molded product, and a matrix resin is injected, or FRP material, that is, SMC (sheet molding compound) or BMC (bulk molding compound). Etc. are inserted and fitted, heated and pressurized in the mold, and the FRP material is melted and thermoset to form an FRP molded product. Further, the mold is opened once and provided between the FRP molded product and the mold surface. The in-mold coating composition is poured into the gaps, the mold is closed again, heated and pressurized, and molded into the desired shape, thereby obtaining a molded product coated with the in-mold coating composition.

  Hereinafter, for convenience, one mold may be referred to as a “lower mold” and the other mold may be referred to as an “upper mold”.

<Fiber-reinforced plastic material>
As the reinforcing fiber used for the FRP material, any known reinforcing fiber such as glass fiber, aramid fiber, and carbon fiber can be used, and a plurality of types of reinforcing fibers can be used in combination. In particular, carbon fibers are excellent in specific strength and specific elastic modulus. In order to obtain an FRP material that is lightweight and has excellent mechanical properties, it is preferable to use carbon fibers alone or in combination with other reinforcing fibers. It is preferable that the ratio of the carbon fiber in the reinforcing fiber is 10 to 100% by mass.

  An epoxy resin is used as the matrix resin of the FRP material used in the in-mold coating method of the present invention. Any arbitrary epoxy resin can be applied as long as it is suitable for the FRP material, and the curing agent is at least one selected from amine compounds, acid anhydride compounds, polyimide compounds and imidazole compounds. preferable.

  The heating temperature at the time of molding the FRP material is arbitrarily determined depending on the molding time, the type of the FRP material, etc., but it is usually appropriate to set the mold temperature to 80 to 200 ° C. It is desirable that the mold is set at the above temperature and maintained at that temperature until a cured film described later is obtained.

The molding pressure of the FRP material is arbitrarily determined depending on the heating temperature, the type of the FRP material, and the like, but usually 50 to 250 kgf / cm ² is appropriate.

The molding time of the FRP material may be until the FRP material completely completes the thermosetting reaction. However, when the coating composition to be described later is injected, it only needs to be cured to a strength that does not impair the shape of the molding. Second to 180 minutes is appropriate. Next, the upper mold is separated from the surface of the molded product, and after providing a gap larger than a desired cured film thickness to be described later but insufficient to release the fitting of the mold, or after fitting the mold While maintaining the molding pressure in the combined state or after reducing the pressure to about 10-40 kgf / cm ² , the in-mold coating composition is of an amount sufficient to obtain a desired film thickness, preferably a cured film of 10-1000 μm. The object is press-fitted (injection injection) between the upper mold and the surface of the molded product. Then, while maintaining the heating temperature substantially at the above temperature, the inner coating composition uniformly covers the surface of the molded article and is (re) pressed to about 20 to 140 kgf / cm ² so as to penetrate, until a cured film is formed. Maintain for about 30-180 seconds. After the cured film is thus formed on the surface of the molded product, the mold is opened, and the obtained in-mold coated molded product is taken out from the mold.

  The molding time from the placement of the reinforcing fiber to the removal of the in-mold coated molded product from the mold is preferably 5 to 15 minutes from the viewpoint of productivity.

<Method for forming coating film>
In the coating film forming method of the present invention, at least one colored coating film is formed on the coated molded article.

  Examples of the colored coating composition that forms the colored coating include an intermediate coating composition and a colored base coating composition. For example, an organic solvent-based, water-based or powder-based coating material containing a resin component, a colorant and a solvent, and further blended with a delustering agent or a usual coating additive as required can be used.

  As the resin component, normal drying resins, normal curing resins, and heat curing resins can be used. Examples include acrylic resins, vinyl resins, polyester resins, and melamine resins and (block) poly resins. A crosslinking agent such as an isocyanate compound can also be used in combination.

  As the colorant, any conventionally known color pigments or bright pigments can be used. Examples of the color pigment include inorganic pigments such as titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chromium yellow, chromium oxide, Prussian blue, and cobalt blue; azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, Examples thereof include organic pigments such as selenium pigments and perylene pigments. A bright pigment is a pigment that imparts a glittering sensation or light interference to a coating film. For example, it is coated with scaly aluminum, bronze, stainless steel, nickel powder, mica-like iron oxide, mica, or metal oxide. And mica. Colorants are not limited to those shown here.

  Furthermore, as the delustering agent for adjusting the gloss of the coating film, calcium carbonate, kaolin, clay, diatomaceous earth, white carbon, talc, silica powder, wollastonite and the like can be used. Usable as the solvent are ordinary organic solvents for paints and water.

The coating film forming method for forming the colored coating film is not particularly limited.
1-coat 1-bake method (1C1B), in which a base coating composition is applied and heat-cured
A two-coat one-bake method (2C1B) in which a base coating composition is applied and a clear coating composition is applied thereon without curing by heating, and both coating films are cured simultaneously.
2 coat 2 bake method (2C2B) which paints base paint composition, heat cures, paints clear paint composition on it and cures clear paint film,
A first base coating composition (for example, an intermediate coating composition) is applied, and a second base coating composition (colored base coating composition) is applied without heating and curing, and a clear coating composition is not cured without curing. 3 coat 1 bake method (3C1B) which paints thing, and hardens these three layer coating films simultaneously,
The first base paint composition is applied, heat-cured, the second base paint composition is applied, the clear paint composition is applied without curing, and the three coats 2 are simultaneously cured. Bake method (3C2B),
Examples include a 3-coat 3-bake method (3C3B) in which the first base paint composition is heat-cured, the second base paint composition is applied, this is cured, and a clear paint composition is applied and cured. .

  In the multilayer coating film forming method, a conventionally known thermosetting clear coating composition paint can be used as the clear coating composition.

  A heating means is not specifically limited, For example, drying equipment, such as a hot air furnace, an electric furnace, and infrared induction heating, can be applied.

  When the coated colored coating composition is cured by heating, the curing temperature is, for example, 60 to 160 ° C., preferably 80 to 140 ° C., and can be cured by heating for 10 to 40 minutes. Alternatively, the coating may be left standing (setting) at room temperature for several minutes after coating, or preheated at 40 to 100 ° C. for 1 to 20 minutes, followed by heat curing.

  Next, when forming a clear coat, the clear coating composition is applied so that the film thickness is 10 to 70 μm in terms of cured film thickness, and the heating temperature is 60 to 180 ° C., preferably 80 to 160 ° C. It is preferred to cure by crosslinking for ~ 25 minutes.

  The coating method of each coating composition can be performed by a conventionally known method, for example, spray, roll coater, gravure coater, screen, spin coater, flow coater, electrostatic coating or the like.

  It is preferable to coat the colored coating film so that the cured film thickness is 10 to 50 μm.

  These single films or multi-layer films may have a concealing property such that the coating surface of the lower layer cannot be seen through the single coating film, or may have transparency so that it can be seen through. .

  Hereinafter, the present invention will be described in more detail with reference to examples. “Part” and “%” indicate “part by mass” and “% by mass” unless otherwise specified. In addition, the measurement in a manufacture example was performed using the following analyzers and measuring methods in addition to the analyzer described in this specification.

The measurement of the viscosity was performed using an E-type viscometer (Toki Sangyo, RE80 type, shear rate: 10 s ⁻¹ , measurement temperature 20 degrees).

(Production Example 1) In-mold coating composition No. 1 production
As component (A), purple light ^{(registered trademark)} UV-2000B (Note 1) 40.0 parts, as component (B) 1,4-butanediol diacrylate [molecular weight 198] 55.0 parts, as component (C) Aronix ^{(Registered trademark)} M-400 (Note 6) 5.0 parts, Ketjen Black ^{(registered trademark)} EC300J (Note 9) 3.0 parts, and BYK ^{(registered trademark)} -9076 (Note 10) 1.0 part After mixing, 180 parts of 2.0 mmφ glass beads were added and dispersed for 1 hour in Scandex SO400 manufactured by FM Corporation to obtain a dispersion. 30.0 parts of talc MA (Note 8) is mixed into the dispersion, stirred at 1500 rpm for 30 minutes using a disper, and then mixed with 1.0 part of t-octylperoxyoctoate as the organic peroxide (D). In-mold coating composition No. having a viscosity of 5500 mPa · s (20 ° C.). 1 was obtained.

(Production Examples 2 to 21) In-mold coating composition No. Production of 2-21
In Production Example 1, in-mold coating composition No. 1 having a solid content of 100% shown in Table 1 was prepared in the same manner as in Production Example 1 except that the composition of each component was as shown in Table 1. 2-No. 21 was obtained. In addition, the compounding quantity of Table 1 shows the compounding quantity of solid content. Moreover, the viscosity of the obtained in-mold coating composition is also shown.

Note 1) A-1: Purple light ^{(registered trademark)} UV-2000B, bifunctional urethane acrylate, solid content 100% by mass, weight average molecular weight 13,000, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.
Note 2) A-2: Lipoxy ^{(registered trademark)} R-802, bisphenol A type vinyl ester resin, weight average molecular weight 5,000, manufactured by Showa Denko KK
Note 3) A-3: Sandoma ^{(registered trademark)} CU653, unsaturated polyester resin, weight average molecular weight 5,000,
Made by DH Material Co., Ltd.
Note 4) A-4: EBECRYL ^{(registered trademark)} 885, trifunctional polyester acrylate, weight average molecular weight 6,000, manufactured by Daicel-Cytec Corporation,
Note 5) A′-1: EBECRYL ^{(registered trademark)} 4858, bifunctional urethane acrylate, weight average molecular weight 450, manufactured by Daicel-Cytec Corporation.

Note 6) C-1: Aronix ^{(registered trademark)} M400, a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, the dipentaerythritol pentaacrylate content ratio is 40 to 50%, manufactured by Toagosei Co., Ltd.
Note 7) C-2: NK ester 701, glycerin dimethacrylate, weight average molecular weight 228, manufactured by Shin-Nakamura Chemical Co., Ltd.

  Note 8) Talc MA: inorganic filler, hydrous magnesium silicate, average particle size 14 μm, manufactured by Nippon Talc Co., Ltd.

Note 9) Ketjen Black ^{(registered trademark)} EC300J: Conductivity imparting agent, carbon black, manufactured by Lion Corporation.

Note 10) BYK ^{(registered trademark)} -9076: Wetting and dispersing agent, alkylammonium salt of polymer copolymer, manufactured by Big Chemie Co., Ltd.

(Example 1)
Epicote 828 (Note 11) 100 parts,
40.0 parts methyl nadic anhydride,
2-ethyl-4-methylimidazole 1.0 part dialkylsulfosuccinate 2.0 part is mixed,
These resins were placed in a 40 ° C. bath, impregnated with carbon fiber TR-30G manufactured by Mitsubishi Rayon Co., Ltd. to form a flat plate, and the coating composition injection apparatus was molded at a molding pressure of 100 kg / cm ² and a heating temperature of 140 ° C. for 60 minutes. . Subsequently, in-mold coating composition No. 1 shown in Table 1 was obtained between the obtained molded product and the mold. 1 was injected and the pressure was increased to 60 kg / cm ² and maintained for 90 seconds while maintaining 140 ° C., and then the pressure was reduced, and the coated molded article coated with the coating film thickness shown in Table 2 was taken out. Table 2 shows the results of evaluation of adhesion (base material) of the coated molded product formed with the in-mold coating composition at this time.

  (Note 11) Epicoat 828 (Ep828): bisphenol A type epoxy resin, weight average molecular weight 380, manufactured by Mitsubishi Chemical Corporation.

Next, an intermediate coating composition (trade name “TP-65-2”, manufactured by Kansai Paint Co., Ltd., polyester resin / amino resin organic solvent type coating composition) is applied to the resulting coated molded article to a thickness of 35 μm. The coating was cured by heating at 140 ° C. for 30 minutes.
Next, a top-coated base coat coating composition (trade name “WBC-713T”, manufactured by Kansai Paint Co., Ltd., acrylic resin / amino resin aqueous coating composition) was applied to a film thickness of 20 μm, and allowed to stand for 2 minutes. Preheating was performed at 80 ° C. for 3 minutes.
Next, an overcoating clear coating composition (trade name “Magicron KINO-1210”, manufactured by Kansai Paint Co., Ltd., acrylic resin organic solvent coating composition) is applied on the uncured coating surface to a film thickness of 35 μm, After being left for 7 minutes, both coatings were cured simultaneously by heating at 140 ° C. for 30 minutes. Thus, a coated article in which a multilayer coating film composed of an intermediate coating film, a base coating film and a clear coating film was formed on the coated molded article was obtained. The obtained coated article was cut into a size of 100 mm × 150 mm to obtain a test plate. Table 2 shows the evaluation results used for the evaluation of the obtained test plate.

(Examples 2-15, Comparative Examples 1-6)
Except for the in-mold coating composition type, molding conditions (heating temperature and time) and coating film thickness described in Table 2, each test plate was prepared in the same manner as in Example 1 and subjected to various evaluations. . The evaluation results are shown in Table 2.

  (Note 12) “-” in Table 2 indicates that the test was not conducted.

≪Performance evaluation≫
(Note 13) Adhesion (base material):
Make 100 2mm x 2mm gobangs on the coated surface of the coated molded product so as to reach the base of the molded product according to JIS K 5600-5-6 (1990), and apply adhesive tape to the surface. The number of goby eye coatings remaining on the coating surface after peeling off rapidly was evaluated.
A: Remaining number / total number = 100/100, no missing edges ○: Remaining number / total number = 100/100, no edges missing Δ: Remaining number / total number = 99 to 90/100 X: Remaining number / total number = 89 or less / 100.

(Note 14) Adhesion (colored coating film):
Each test plate was evaluated by performing the same adhesion test as in the above (Note 12).

(Note 15) Finishability:
<Appearance (visual)>
About each test board, the presence or absence of a nest hole, a pinhole, a microcrack, or the carbon fiber shape float (fiber pattern) was confirmed visually, and the following reference | standard evaluated.
◎: Nest hole, pinhole, minute crack or carbon fiber shape floating cannot be confirmed at all ○: Nest hole, pinhole, minute crack or carbon fiber shape floating cannot be visually confirmed △: Nest hole, pinhole, A slight crack or carbon fiber-shaped float can be confirmed x: Nest hole, pinhole, minute crack or carbon fiber-shaped float can be confirmed
<Surface roughness>
About each test board, the surface roughening degree-center average roughness (Ra) was measured, and the sealing property was evaluated according to the following criteria.
The center average roughness (Ra) of the surface of each test plate was measured using SURFCOM 130A manufactured by Tokyo Seimitsu under the conditions of a cutoff value of 2.5 mm, a measurement range of 25 mm, and a measurement speed of 0.3 mm / min.
A: The center average roughness (Ra) is less than 0.2 B: The center average roughness (Ra) is 0.2 or more and less than 0.35 Δ: The center average roughness (Ra) is 0.35 Or more and less than 0.50 x: center average roughness (Ra) of 0.5 or more.

(Note 16) Water resistance:
Each test plate was immersed in warm water of 40 ° C. and taken out after 240 hours, and the appearance (visual observation) of the coating film and the adhesion test similar to the above Note 12 were conducted, and evaluated according to the following criteria.
◎: No abnormality is observed in the coating film, remaining number / total number = 100/100, no missing edge ○: No abnormality is observed in the coating film, remaining number / total number = 100/100, edge There is a chipping △: There is a slight blister on the coating surface,
Or remaining number / total number = 99 to 90/100 ×: blister on the coating film surface,
Or remaining number / total number = 89 or less / 100.

Claims (4)

The fiber reinforced plastic material is heated and molded in the mold, and then the in-mold coating composition is injected between the obtained molded product and the inner wall of the mold to cure the in-mold coating composition, and then the coating is performed. In the in-mold coating method including the step of taking out the formed molded product from the mold,
The matrix resin used for the fiber reinforced plastic material is an epoxy resin,
And the in-mold coating composition comprises:
(A) a resin having a weight average molecular weight of 3,000 to 80,000 selected from a polymerizable unsaturated group-containing urethane resin, a polymerizable unsaturated group-containing epoxy resin, and a polymerizable unsaturated group-containing polyester resin;
(B) a compound represented by the following general formula (I) having a molecular weight of 156 to 280,

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents a linear, branched or cyclic alkylene group having 2 to 8 carbon atoms, an alkoxyalkylene group having 2 to 8 carbon atoms, or 2 to 2 carbon atoms. 8 halogenated alkylene groups, polyethylene glycol skeleton excluding terminal hydroxyl groups, polypropylene glycol skeleton excluding terminal hydroxyl groups, polybutylene glycol skeletons excluding terminal hydroxyl groups, neopentyl glycol excluding terminal hydroxyl groups, and allyl groups. A divalent organic group having no
(C) a compound having one or more hydroxyl groups and two or more (meth) acryloyl groups in one molecule, and (D) an organic peroxide, and component (A), component (B) and component ( The solid content of the component (A) is 5 to 80 parts by mass based on 100 parts by mass of the total solid content of C),
The solid content of the component (B) is 10 to 85 parts by mass,
The solid content of the component (C) is 1 to 10 parts by mass,
The solid content of component (D) is 0.1 to 5 parts by mass,
An in-mold coating method characterized in that: The in-mold coating method according to claim 1, wherein the curing agent used for the fiber reinforced plastic material is at least one selected from an amine compound, an acid anhydride compound, a polyimide compound, and an imidazole compound. A method for producing a molded product , comprising a step of forming a cured film on the surface of a molded product by the in- mold coating method according to claim 1. A method of forming a coating film molding, characterized in that at least one layer forming a colored coating film molded type product according to claim 3.